BITSAT2012ChemistryChemical Bonding and Molecular StructureActual
Bond enthalpies of H ₂, X ₂ and HX are in the ratio 2: 1: 2 . If enthalpy of formation of HX is -50 ~kJ mol ⁻¹, the bond enthalpy of X ₂ is
Options
- A100 ~kJ ~mol ⁻¹
- B300 ~kJ ~mol ⁻¹
- C200 ~kJ ~mol ⁻¹
- D400 ~kJ ~mol ⁻¹
Correct answer
A. 100 ~kJ ~mol ⁻¹
Step-by-step solution
1 2 H ₂+ 1 2 X ₂ HX Let the bond enthalpy of X - X bond be x . H _ f ( HX )=-50= 1 2 H _ H - H + 1 2 H _ X - X - H _ H - X = 1 2 2 x+ 1 2 x-2 x= -x 2 x=50 2=100 ~kJ ~mol ⁻¹